Vivid3D is a C++ IDE/3D engine, with python scripting.
PyCAPGE - Python Classic Adventure Point and Click Game Engine
A free 3D game engine to create games and realtimes scenes for Windows
Spring is a free RTS engine developed for Windows, Linux and Mac OS X.
2D Game Engine
Modern 3D engine and IDE written using C# and C++.
IRB is a game creation toolkit
Open Game Bootstrap
Gorgon Game Engine (GGE) is a C++ game engine that handles many tasks.
cross-platform 2d game engine
SDK for Resident Evil Games
Simple Point & Click Game
Make games with Lego-like building blocks